rudimentary config gui (again)

src/main/kotlin/moe/nea/notenoughupdates/util/data/DataHolder.kt

@@ -0,0 +1,60 @@
+package moe.nea.notenoughupdates.util.data
+
+import java.nio.file.Path
+import kotlinx.serialization.KSerializer
+import kotlin.io.path.exists
+import kotlin.io.path.readText
+import kotlin.io.path.writeText
+import moe.nea.notenoughupdates.NotEnoughUpdates
+
+abstract class DataHolder<T>(
+    val serializer: KSerializer<T>,
+    val name: String,
+    val default: () -> T
+) : IDataHolder<T> {
+
+
+    final override var data: T
+        private set
+
+    init {
+        data = readValueOrDefault()
+        IDataHolder.putDataHolder(this::class, this)
+    }
+
+    private val file: Path get() = NotEnoughUpdates.CONFIG_DIR.resolve("$name.json")
+
+    protected fun readValueOrDefault(): T {
+        if (file.exists())
+            try {
+                return NotEnoughUpdates.json.decodeFromString(
+                    serializer,
+                    file.readText()
+                )
+            } catch (e: Exception) {/* Expecting IOException and SerializationException, but Kotlin doesn't allow multi catches*/
+                IDataHolder.badLoads.add(name)
+                NotEnoughUpdates.logger.error(
+                    "Exception during loading of config file $name. This will reset this config.",
+                    e
+                )
+            }
+        return default()
+    }
+
+    private fun writeValue(t: T) {
+        file.writeText(NotEnoughUpdates.json.encodeToString(serializer, t))
+    }
+
+    override fun save() {
+        writeValue(data)
+    }
+
+    override fun load() {
+        data = readValueOrDefault()
+    }
+
+    override fun markDirty() {
+        IDataHolder.markDirty(this::class)
+    }
+
+}